1. Field of the Invention
The invention relates in general to a color tracking method for a panel and an associated modifying module, and more particularly, to a method for enhancing color tracking accuracy through modifying display values measured by a color meter and an associated modifying module.
2. Description of the Related Art
Display panels, e.g., color liquid crystal display (LCD) panels for monitors and televisions, being capable of presenting diversified multimedia information, have become essential parts of the modern information society.
Stereotypical conventional Information playback operations of a display panel are described as follows. The panel is driven by a controller (e.g., a control chip), which receives a video stream comprising a series of input values from a signal source. The controller then provides driving signals to pixels of the panel according to the series of input values, so as to drive the pixels to display. Each input value (r_in, g_in, b_in) includes three input components, e.g., a red component r_in, a green component g_in and a blue component b_in, each of which may have a value between 0 and 255. That is, with different combinations of input component values, the input value is able to describe 256*256*256 different colors.
However, due to discrepancies in characteristics of different panels, actual colors presented by the different panels with the same input values corresponding to driving signals may be different. To compensate the discrepancies between the panels, the controller needs to perform color tracking on the panels individually. In color tracking, a color meter first measures colors displayed on a display panel to obtain measured results; according to the measured results, display settings are then adjusted to normalize display effects, so that the display effects of the colors displayed on the different panels are inclined to consistency. For example, color temperatures of different grayscales of different panels are tuned to approximate a same target temperature (e.g., 6500 Kelvin degrees). For example, the color meter can be a color temperature meter for measuring a display value (X, Y, Z) of a color displayed on the panel. The display value (X, Y, Z) includes three display components X, Y and Z. It is to be noted that, a value of the display component Y alone corresponds to a brightness of a color, and a color temperature of a color is determined by values of the three display components X, Y, and Z. The controller for controlling the panel converts the input components of the input values into corresponding driving signals according to display settings.
A conventional color tracking approach is to be described below. In the prior art, pixels of a panel sequentially receive a total of Np number of grayscale blending input values W(1)=(vin(1), vin(1), vin(1)), W(2)=(vin(2), vin(2), vin(2)), . . . W(Np)=(vin(Np), vin(Np), vin(Np)). Each of the input values includes three input components (r_in, g_in, b_in), as previously mentioned. The Np number of grayscale blending input values respectively correspond to a grayscale brightness W(i), where i=1 to Np. While receiving the grayscale blending input values, the color meter measures the corresponding Np display values Wp(1)=(Xw(1), Yw(1), Zw(1)), Wp(2)=(Xw(2), Yw(2), Zw(2)), . . . Wp(Np)=(Xw(Np), Yw(Np), Zw(Np)). Each of the display values includes three display components (X, Y, Z), as previously mentioned. The display values also respectively correspond to a measured grayscale brightness Wp(i), where i=1 to Np. In addition, the panel may also receive and display three monochromatic input values R(Np)=(vin(Np), 0, 0), G(Np)=(0, vin(Np), 0), and B(Np)=(0, 0, vin(Np)), which respectively correspond to a monochromatic brightness R(Np), G(Np), and B(Np). Three corresponding display values Rp(Np)=(Xr(Np), Yr(Np), Zr(Np)), Gp(Np)=(Xg(Np), Yg(Np), Zg(Np)) and Bp(Np)=(Xb(Np), Yb(Np), Zb(Np)) are then measured. Similarly, the three display values may respectively correspond to a measured monochromatic brightness Rp(Np), Gp(Np), and Bp(Np).
Based on color synthesis theories, grayscale blending input values (vin(Np), vin(Np), vin(Np)) are synthesized from the three monochromatic input values (vin(Np), 0, 0), (0, vin(Np), 0) and (0, 0, vin(Np)), i.e. R(np)+G(Np)+B(Np)=W(Np). Similarly, the display value (Xw(Np), Yw(Np), Zw(Np)) shares the same feature; that is, Rp(Np)+Gp(Np)+Bp(Np)=Wp(Np). Furthermore, the display component Xw(Np) is theoretically equal to a sum Xr(Np)+Xg(Np)+Xb(Np) of the display components Xr(Np), Xg(Np), and Xb(Np), and the display component Zw(Np) is theoretically equal to a sum Zr(Np)+Zg(Np)+Zb(Np) of the display components Zr(Np), Zg(Np), and Zb(Np).
In the prior art, it is assumed based on color synthesis theories that, Xw(i)=Xr(i)+Xg(i)+Xb(i), Yw(i)=Yr(i)+Yg(i)+Yb(i), and Zw(i)=Zr(i)+Zg(i)+Zb(i). It is also assumed that the ratio of Rp(i) to Wp(i), the ratio of Gp(i) to Wp(i), and the ratio of Bp(i) to Wp(i) are maintained almost unchanged within a range between i=1 and Np. Thus, interpolation is performed on the display values (Xr(Np),Yr(Np),Zr(Np)), (Xg(Np),Yg(Np),Zg(Np)), (Xb(Np),Yb(Np),Zb(Np), and (Xw(1),Yw(1),Zw(1)), as well as (Xw(Np),Yw(Np),Zw(Np)) to obtain a display value (Xr(i), Yr(i), Zr(i)) corresponding to the input value (vin(i), 0, 0), a display value (Xg(i), Yg(i), Zg(i)) corresponding to the input value (0, vin(i), 0), and a display value (Xb(i), Yb(i), Zb(i)) corresponding to the input value (0, 0, vin(i)), where i=1 to (Np−1). According to the display values obtained through interpolation, a corresponding display setting may be obtained through a display setting algorithm.
However, in practice, it is discovered that not only grayscale color temperatures are inconsistent but also the grayscale color temperatures cannot reach the target temperatures after the adjustment in the prior art, such that certain offset exists between the grayscale color temperatures and the target color temperature. Therefore, there is a need for a solution for improving the prior color tracking technique in the prior art.